1. Field of the Invention
The present invention pertains to an evaluation method and an evaluation device for evaluating the optical properties of a spectacle lens, and in particular, to a spectacle lens evaluation method and evaluation device with which optical properties can be found taking into consideration the state in which the spectacle lens is worn and the direction of the line of vision of the eye.
2. Description of the Related Art
Spectacle lenses are produced and finished in accordance with the optimized specifications of designers, and lens meters are used to evaluate the properties of a finished spectacle lens. Determination with a lens meter involves projecting parallel light beams perpendicular to the lens surface and determining lens power, etc. Moreover, lens meters that determine the addition are also known. Determinations with these lens meters are usually determinations at a spot on the lens. In contrast to this, devices that determine optical properties over a wide region on the lens have recently been presented (for example, refer to Japanese National Publication No. Hei 10-507825 and Japanese Laid-Open Patent No. Hei 8-304228).
Incidentally, it is necessary to take into consideration the differences from conventional optical systems (cameras and telescopes) when evaluating the optical properties of a spectacle lens. That is, it is possible to project people to be photographed over a wide range all at once on the film surface with a conventional optical system, such as a camera, but when the eye looks over a wide range, the eyeball captures the object as it turns around its center of rotation (eyeball movement) and moves its line of vision. This is why not all objects reflected on the retina of the eye are perceived as clear objects and only the narrow region at the fovea with high resolution can be clearly seen.
On the other hand, it is not possible to determine the light rays or light beams in the direction of the field of vision that pass through the center of rotation of the eyeball other than on the optical axis of the spectacle lens, and the refractive index of the apex in the direction of the field of vision that passes through the periphery of the spectacle lens, etc., cannot be correctly determined with a lens meter.